The present invention relates generally to methods and apparatus for video distribution in a wireless communication system and, more particularly, to methods and apparatus for coding video for transmission over wireless networks to mitigate fast fading effects.
Mobile communication devices, such as cellular telephones and personal digital assistants, are now capable of high-speed data communications. Users of mobile communication devices can now surf the web, send and receive email messages, chat with friends, view images, play music, and perform other tasks that previously required a computer. With increasing data rates and bandwidths, along with larger displays, it is now possible to stream high quality video content from a video server to users for viewing on their mobile communication devices.
Selective fading can present a problem when delivering video content over wireless networks. Mobile communication devices may experience rapid changes in channel conditions, particularly in indoor environments. If channel conditions degrade, it may not be possible to support the data rates necessary to deliver high quality video content. In such instances, the video output to the display may be corrupted, or possibly even interrupted, resulting in an unfavorable user experience. Link adaptation responsive to changing channel conditions could be used to mitigate the effects of fading. However, link adaptation requires feedback from the receiving device to the transmitting device. Further, link adaptation may be more useful in slow fading conditions than in fast fading conditions due to the lag between the time that the receiving device reports channel conditions and the time that the modulation and coding can be adapted.
Accordingly, there is a need for new methods to mitigate the effects of fast fading when delivering video to mobile communication devices over wireless networks.